Mixing device for gluing wood shavings

ABSTRACT

A device for applying glue to wood shavings, fibers and similar cellulose containing materials and mixtures in a mixing container, according to which a feeding conduit feeds liquid glue into an annular chamber formed by the outside of the feeding conduit and the inside of a hollow rotatable shaft surrounding the feeding conduit. The liquid glue is then passed through a longitudinal passage in a mixing tool which is connected to the hollow shaft for rotation therewith and passes outwardly to an area near the free end of the mixing tool which free end is intended to immerse into the mixture in the mixing container.

United States Patent Lodige et a1. Dec. 24, 1974 MIXING DEVICE FOR GLUING WOOD 3,466,015 9/1969 Lodige et al.... 259/25 x SHAVINGS 3,734,471 5/1973 Engels 259/10 x Inventors: Wilhelm Lodige, Elsener Str. 9c; Fritz Lodige, Leuschner Str. 12; Josef Lucke, Im Lohfeld 13, all of 479 Paderborn, Germany Filed: Dec. 26, 1972 Appl. No.: 318,648

Foreign Application Priority Data Dec. 23, 1972 Germany 2164380 References Cited UNITED STATES PATENTS 12/1967 Peach 259/25 Primary Examiner-I-Iarvey C. I-Iornsby Assistant ExaminerPhilip R. Coe Attorney, Agent, or Firm-Walter Becker [5 7 ABSTRACT A device for applying glue to wood shavings, fibers and similar cellulose containing materials and mixtures in a mixing container, according to which a feeding conduit feeds liquid glue into an annular chamber formed by the outside of the feeding conduit and the inside of a hollow rotatable shaft surrounding the feeding conduit. The liquid glue is then passed through a longitudinal passage in a mixing tool which is connected to the hollow shaft for rotation therewith and passes outwardly to an area near the free end of the mixing tool which free end is intended to immerse into the mixture in the mixing container.

. 12 Claims, 3 Drawing Figures MIXING DEVICE FOR GLUING WOOD SHAVINGS The present invention relates to a device for gluing wood shavings, fibers and similar material mixed from wood, waste bagasse or the like, preferably cellulosecontaining substances, which device comprises primarily a substantially cylindrical mixing chamber in which the substances to be glued are circulated by mixing tools which in their turn are journalled on a central drive shaft, which latter serves for feeding the glue liquid.

A device of this type has been described for instance in German Auslegeschrift 1,557,124. According to the device described in said German Auslegeschrift, the hollow drive shaft is provided with radial outlet openings for the glue liquid which latter passes from said outlet openings into radial tubes which protrude beyond the hollow drive shaft. Each of said tubes when viewed in the direction of rotation of the drive shaft is located behind a mixing tool in the form of a mixing arm connected to the hollow shaft.

In view of the relatively high circumferential speed of the mixing tools in mixers of this heretofore known type, an undesired high temperature increase occurs especially in the upper range, at the radially outer ends of the mixing tools which agitate the mixture, as well as at the chamber walls. Such increase in temperature brings about that the liquid glue intermixed with dustshaped mixing material prematurely binds at the heated structural elements thereby causing ever increasing adherence of material. This adherence or accumulation of material drops off from time to time and as agglomerates with increased glue components enters the finish pressed plate where it reduces the quality of such plates sometimes to such an extent that the plates are not usable.

In order to overcome the above mentioned drawbacks, it has been suggested to surround the outer wall of the mixing chamber itself with a cooling jacket so that at least at the outer wall of the mixing chamber accumulations of material in view of increased temperatures will be avoided. A similar liquid cooling is, however, not possible on the mixing tools within the region of the addition of glue because the drive shaft through which alone a feeding and withdrawing of the cooling liquid would be possible for the mixing tools is needed for supplying the liquid glue. On the other hand, it is not economically feasible to design the drive shaft so that it can be used for simultaneously feeding and withdrawing cooling liquid. Therefore, it was heretofore necessary to do without an effective liquid cooling of the mixing tools for the purpose of effectively eliminating the above mentioned disadvantageous results of too high a heating.

Therefore, it is an object of the present invention to provide a device for gluing chips, fibers and similar mixtures of wood, waste bagasse or the like, which will overcome the above mentioned drawbacks without giving up the supply of liquid glue through an inner feeding means.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawing, in which:

FIG. 1 illustrates a section through the mixing tool according to the invention, which section is effected perpendicularly with regard to the axis of the drive shaft.

FIG. 2 shows the section taken along the line ll II of FIG. 1.

FIG. 3 is a section taken along the line "I III of FIG. 1.

The device according to the present invention is characterized primarily in that in the lower range of each mixing tool there is provided at least one inlet opening for the glue fluid conveyed through the interior of the drive shaft and is furthermore characterized in that there is provided at least one feeding passage extending from the lower portion of the mixing tool to its upper portion, and there is furthermore provided at least one outlet opening for the glue liquid in the radial outer range of the mixing tool. In this way, the glue fluid itself serves as cooling fluid whereby in a surprisingly simple manner there has been realized not only a liquid cooling of the mixing tools without the provision of additional structural elements and without giving up the advantages of a liquid feed radially inwardly, but in view of the employment of mixing tools there has been obtained over heretofore known arrangements of the type involved a reduction in the structural element and thereby also in the cost of production of devices of the type involved.

Over the heretofore known arrangements of the type involved, there occurs not only no decrease in the splitting up and distribution of the liquid glue, but to the contrary an improvement is obtained in this respect inasmuch as the tools, the upper range of which extends into the flow of the mixture, can without difficulties be provided with outlet openings for the glue liquid so that a splitting up and distribution of the liquid glue can be realized which can hardly be surpassed.

According to a preferred embodiment of the invention, the outlet openings for the liquid glue are provided radially inwardly of the upper range of the mixing tool extending into the mixture whereby the circulating flow of mixture is in the heretofore known customary manner sprayed from the inside, preferably, however, only with a portion of the total quantity of glue liquid. Particularly advantageous are outlet openings in the upper portion of the mixing tool which immerses into the mixture, and, more specifically, in such a way that at least these outlet openings are arranged on that side of the mixing tool which when considering the direction of rotation of the mixing tool forms the rear side. Consequently, glue is conveyed to the turbulent path which, when considering the direction of rotation of the tool, is located behind the mixing tools, whereby an immediate mixing in and an immediate wiping by shaving on shaving friction is effected within the region of the turbulent zone without permitting any formation of lumps. Furthermore, the feeding of glue from the mixing tool is aided by the under-pressure on that side of the tool which, when considering the direction of rotation of the tool, is the rearward side. The feeding of glue from the mixing tool can furthermore be aided advantageously by arranging the outlet openings so that when viewing in the direction of flow of the mixture, the outlet openings are inclined from radially inwardly to radially outwardly.

In an economically favorable manner, the mixing tool may be formed by a thick walled tube. Functionally more favorable, however,- is a design of the mixing tool in such a way that in cross section the tool has a dropshaped streamline contour, the tip of which, however, is located in front when considering the direction of rotation. In this way, the shavings are split up by the mixing tools moving therethrough while no excessive resistance is encountered and therefore the development of friction and heat is held within compatible limits. Simultaneously, it will be assured that a sufficient relative velocity prevails between the rotating flow of material and the driving mixing tools. This relatively velocity is a measurement for the under-pressure behind the mixing tools and for the degree of the prevailing turbulence.

A flow technical improvement can furthermore be realized according to the invention by designing the rearward confining surface of the mixing tool in such a flattened form that the spacing of its rearmost point when considering the direction of rotation, from the plane of the greatest tool width is less than the spacing of the front tip of the tool cross section from said plane, said rearward confining surface of the mixing tool comprising the outlet openings for the liquid glue.

In this way, a definite tearing off of the flow within the region of the greatest width of the tool transverse to the direction of rotation and with subsequent strong turbulence of the air-mixture material entering from the sides is realized within the region behind the mixing tool. According to a particularly preferred embodiment of the invention, the exit openings for the glue liquid lead into the vicinity of the maximum width of the mixing tool. In this way, the glue liquid is introduced directly into the strong turbulences which form within the marginal region of the path of movement directly behind the mixing tool, where an immediate intermixing and intensive distribution is effected.

Referring now to the drawing in detail, the glue fluid is fed through a feeding pipe which is coaxially arranged within a hollow drive shaft. The glue fluid passes through openings 12 in the mantle of the feeding pipe 10 into the annular chamber 13 between the feeding pipe 10 and the outer wall of the rotating drive shaft 11. In the annular chamber 13, the glue fluid is rotated by friction on the inner wall of pipe 13 and in the form of a film deposits on the outer wall of the annular chamber 13. Due to centrifugal forces, the glue fluid is, through a further opening 14, conveyed to an inlet opening 15 in the lower region of the mixing tool 16 which forms a mixing arm. From here the glue fluid passes into a feeding passage 18 which leads into the upper portion 17 of the mixing tool 16.

The feeding passage 18 is in the specific embodiment shown in the drawing designed as a bore extending through the entire length of the mixing tool 16. However, if desired, instead there could be provided a blind bore which is open in the inner range of the mixing tool 16. A stopper, for instance in the form of a threaded closure member 19, could be provided for closing the outer end of a bore. extending throughout the length of the tool so that if necessary or desired the cleaning of the conveying passage 18 would be greatly facilitated by temporarily removing the stopper. Advantages with regard to cleaning could also be realized by not welding the mixing tool 16 to the driving shaft 11 as shown in the drawing but detachably connecting the mixing tool 16 to the drive shaft 11 for instance by a screw connection.

In the specific embodiment shown in the drawing, the mixing tool 16 is formed by a substantially circular segmental flow body with a tip which, when considering the direction of rotation indicated by the arrow 20, is located in front. Such an arrangement has functional advantages over the employment of a correspondingly thick walled tube. Among these advantages particularly lower cost may be mentioned.

When the mixing tool moves through the flow of material to be mixed, a relatively low flow resistance with correspondingly reduced friction and heat development is realized in view of the substantially bladeshaped front side of the mixing tool. This reduced flow resistance brings about that the speed of the rotating flow of material considerably lags behind the speed of the mixing tool 16 so that with the still not excessive heat development the formation of a considerable under-pressure behind the back side of the mixing tool 16 is possible and consequently a strong turbulence path. An undue heating up in spite of the considerable relative velocity of the mixing tool 16 in the flow of material is prevented by the intensive liquid cooling of the liquid glue which is passed through the feeding passage 18 into the upper range 17. It will be appreciated that the intensive cooling effect of the liquid glue makes itself fully felt particularly in the upper range 17 in view of the outlet openings 21 and 22 in'said upper range. The arrangement of outlet openings 21 and 22 in the upper end of the feeding passage 18 prevents at said upper end the formation of heat storing border layers of the liquid glue and brings about a continuous sweeping of the heated inner surfaces of the mixing tool 16 in the upper range 17 by fresh and cool liquid glue.

The outlet openings 21 and 22 are, when viewed in the direction of rotation indicated by arrow 20, arranged in the rearward portion of the mixing tool 16 and lead into the rear confining wall 23 of the mixing tool 16. The outlet openings 21 and 22 when viewed in the direction of flow indicated by the arrow 24 are radially inwardly and radially outwardly inclined (FIG. 1). In view of the reduced deviation of the'direction of flow inherent thereto, in particular the outflow resistance is reduced and in cooperation with the underpressure prevailing within the region of the rearward confining wall 23 and in cooperation with the conveying pressure produced by these centrifugal forces, a continuous functionally correct outflow of the glue fluid through the outlet openings 21 and 22 is obtained.

The rear confining wall 23 is only slightly curved or arched so that preferably its rearmost point (when viewed in the direction of rotation indicated by arrow 20) is spaced from the plane of the largest width b of the mixing tool by a distance which is less than the distance between said rearmost point and the front tip of the mixing tool 16 (see FIG. 3). As a result thereof, the flow containing the mixing material and air will tear off at the edges defining the width b of the mixing tool 16 so that within the region behind the rear confining wall 23 of the mixing tool there will develop a strong underpressure and strong cavitation turbulence. In connection with these processes, a particular advantage is obtained by the fact that the outlet openings 21,22 lead in the vicinity of the maximum width b of the mixing tool 16 to the rear confining wall 23 so that the supply of glue liquid is effected directly into the strong lateral marginal turbulence of the path of movement of the mixing tool 16 where the glue liquid is immediately admixed by the intensive turbulence and is intensively intermixed by shaving against shaving friction, and where furthermore due to the components of movement extending transverse to the main circulation of the flow of material, in the area of turbulence a fast transport of the glue into the further surrounding of the path of movement is effected.

It is a matter of course that if necessary also a plurality of outlet openings for the glue fluid may be provided along the conveying passage 18. This may be effected in particular not only in the head range 17 of the mixing tool 16, which head range is immersed into the flow of the material, but may also be effected radially within the mixing tool 16 in such a way that liquid glue exiting through a plurality of narrow bores will from the inside spray the circulating flow of material in a substantially homogeneous and continuous manner.

In view of the employment of glue liquid according to the invention simultaneously for cooling the liquid of the mixing tools, the problem of intensively cooling the mixing tools has been solved while simultaneously by employing the mixing tools for adding liquid glue, a considerable improvement in the glue distribution is realized already at the time the glue is being added.

It is a matter of course that with the device according to the invention, if it should be desired, also liquids other than glue fluid may be admixed to a circulating flow of material provided that analogous problems of an intensive intermixture with simultaneous cooling are to be solved.

it is, of course, to be understood that the present invention is, by no means, limited to the particular showing in the drawing but also comprises any modifications within the scope of the appended claims.

What we claim is:

l. A device for mixing wood shavings, fibers and similar mixtures of wood and waste bagasse, especially cellulose containing materials and for simultaneously adding glue thereto, which includes: a hollow rotatable shaft, feeding conduit means arranged within said rotatable shaft in radially spaced relationship thereto so as to define with said rotatable shaft an annular chamber, said feeding conduit means being adapted to be connected to a supply of liquid glue and being provided with passage means therethrough for conveying liquid glue from said feeding conduit means into said annular chamber, and a longitudinal mixing tool connected to and extending outwardly of said rotatable shaft for rotation in a mixing chamber, said mixing tool having an outer free end and being provided with a longitudinal passage communicating with said annular chamber and with outlet passage means including an outer mouth communicating with said longitudinal passage substantially transverse thereto and leading to the outside of said mixing tool, said outlet passage means being provided near the outer free end of said mixing tool which end is intended to be immersed into material to be mixed in a mixing chamber, the mouth of said outlet passage means being located on the trailing side of said mixing tool when considering its direction of rotation.

2. A device for mixing wood shavings, fibers and similar mixtures of wood and waste bagasse, especially cellulose containing materials and for simultaneously adding glue thereto, which includes: a hollow rotatable shaft, feeding conduit means arranged within said rotatable shaft in radially spaced relationship thereto so as to define with said rotatable shaft an annular chamber, said feeding conduit means being adapted to be connected to a supply of liquid glue and being provided with passage means therethrough for conveying liquid glue from said feeding conduit means into said annular chamber, and a longitudinal mixing tool connected to and extending outwardly of said rotatable shaft for rotation in a mixing chamber, said mixing tool having an outer free end and being provided with a longitudinal passage communicating with said annular chamber and with outlet passage means including an outer mouth communicating with said longitudinal passage substantially transverse thereto and leading to the outside of said mixing too], said outlet passage means being inclined from said longitudinal passage to the outer mouth of said outlet passage means in the direction toward the free end of said mixing tool.

3. A device according to claim 2, in which said mixing tool is formed by a relatively thick-walled tubular member.

4. A device for mixing wood shavings, fibers and similar mixtures of wood and waste bagasse, especially cellulose containing materials and for simultaneously adding glue thereto, which includes: a hollow rotatable shaft, feeding conduit means arranged within said rotatable shaft in radially spaced relationship thereto so as to define with said rotatable shaft an annular chamber, said feeding conduit means being adapted to be connected to a supply of liquid glue and being provided with passage means therethrough for conveying liquid glue from said feeding conduit means into said annular chamber, and a longitudinal mixing tool connected to and extending outwardly of said rotatable shaft for rotation in a mixing chamber, said mixing tool having an outer free end and being provided with a longitudinal passage communicating with said annular chamber and with outlet passage means including an outer mouth communicating with said longitudinal passage substantially transverse thereto and leading to the outside of said mixing tool, said mixing tool having a somewhat triangular cross section including a tip of the triangle forming the leading edge when considering the direction of rotation of said mixing tool.

5. A device according to claim 4, in which said outlet passage means are provided near the outer free end of said mixing tool which end is intended to be immersed into material to be mixed in a mixing chamber.

6. A device according to claim 4, in which the mouth of said outlet passage means is located on the trailing side of said mixing tool when considering its direction of rotation.

7. A device according to claim 4, in which the base of the triangle is concavely curved.

8. A device according to claim 7, in which a base area of the triangular cross section which contains the mouth of said outlet passage means is provided substantially flattened so that the spacing thereof from greatest width of said triangular cross section is less than the distance to the tip of said triangular cross section.

9. A device according to claim 8, in which the mouth of said outlet passage means is located in the vicinity of the greatest width of the mixing tool.

10. A device for mixing wood shavings, fibers and similar mixtures of wood and waste begasse, especially cellulose containing materials and for simultaneously adding glue thereto, which includes: a hollow rotatable shaft, feeding conduit means arranged within said rotatable shaft in radially spaced relationship thereto so as to define with said rotatable shaft an annular chamber, said feeding conduit means being adapted to be connected to a supply of liquid glue and being provided with passage means therethrough for conveying liquid glue from said feeding conduit means into said annular chamber, and a longitudinal mixing tool connected to and extending outwardly of said rotatable shaft for rotation in a mixing chamber, said mixing tool having an outer free end and being provided with a longitudinal passage communicating with said annular chamber and with outlet passage means including an outer mouth communicating with said longitudinal passage substantially transverse thereto and leading to the outside of said mixing tool, the longitudinal passage in said mixing tool extending through the entire length thereof, and a closure member arranged in the outer free end of said mixing tool and thereby sealing said longitudinal passage at the outer free end of said mixing tool.

11. A device according to claim 10, in which said closure member is detachably connected to said mixing tool.

12. A device according to claim 10, in which said mixing tool is detachably connected to said hollow ro- 

1. A device for mixing wood shavings, fibers and similar mixtures of wood and waste bagasse, especially cellulose containing materials and for simultaneously adding glue thereto, which includes: a hollow rotatable shaft, feeding conduit means arranged within said rotatable shaft in radially spaced relationship thereto so as to define with said rotatable shaft an annular chamber, said feeding conduit means being adapted to be connected to a supply of liquid glue and being provided with passage means therethrough for conveying liquid glue from said feeding conduit means into said annular chamber, and a longitudinal mixing tool connected to and extending outwardly of said rotatable shaft for rotation in a mixing chamber, said mixing tool having an outer free end and being provided with a longitudinal passage communicating with said annular chamber and with outlet passage means including an outer mouth communicating with said longitudinal passage substantially transverse thereto and leading to the outside of said mixing tool, said outlet passage means being provided near the outer free end of said mixing tool which end is intended to be immersed into material to be mixed in a mixing chamber, the mouth of said outlet passage means being located on the trailing side of said mixing tool when considering its direction of rotation.
 2. A device for mixing wood shavings, fibers and similar mixtures of wood and waste bagasse, especially cellulose containing materials and for simultaneously adding glue thereto, which includes: a hollow rotatable shaft, feeding conduit means arranged within said rotatable shaft in radially spaced relationship thereto so as to define with said rotatable shaft an annular chamber, said feeding conduit means being adapted to be connected to a supply of liquid glue and being provided with passage means therethrough for conveying liquid glue from said feeding conduit means into said annular chamber, and a longitudinal mixing tool connected to and extending outwardly of said rotatable shaft for rotation in a mixing chamber, said mixing tool having an outer free end and being provided with a longitudinal passage communicating with said annular chamber and with outlet passage means including an outer mouth communicating with said longitudinal passage substantially transverse thereto and leading to the outside of said mixing tool, said outlet passage means being inclined from said longitudinal passage to the outer mouth of said outlet passage means in the direction toward the free end of said mixing tool.
 3. A device according to claim 2, in which said mixing tool is formed by a relatively thick-walled tubular member.
 4. A device for mixing wood shavings, fibers and similar mixtures of wood and waste bagasse, especially cellulose containing materials and for simultaneously adding glue thereto, which includes: a hollow rotatable shaft, feeding conduit means arranged within said rotatable shaft in radially spaced relationship thereto so as to define with said rotatable shaft an annular chamber, said feeding conduit means being adapted to be connected to a supply of liquid glue and being provided with passage means therethrough for conveYing liquid glue from said feeding conduit means into said annular chamber, and a longitudinal mixing tool connected to and extending outwardly of said rotatable shaft for rotation in a mixing chamber, said mixing tool having an outer free end and being provided with a longitudinal passage communicating with said annular chamber and with outlet passage means including an outer mouth communicating with said longitudinal passage substantially transverse thereto and leading to the outside of said mixing tool, said mixing tool having a somewhat triangular cross section including a tip of the triangle forming the leading edge when considering the direction of rotation of said mixing tool.
 5. A device according to claim 4, in which said outlet passage means are provided near the outer free end of said mixing tool which end is intended to be immersed into material to be mixed in a mixing chamber.
 6. A device according to claim 4, in which the mouth of said outlet passage means is located on the trailing side of said mixing tool when considering its direction of rotation.
 7. A device according to claim 4, in which the base of the triangle is concavely curved.
 8. A device according to claim 7, in which a base area of the triangular cross section which contains the mouth of said outlet passage means is provided substantially flattened so that the spacing thereof from greatest width of said triangular cross section is less than the distance to the tip of said triangular cross section.
 9. A device according to claim 8, in which the mouth of said outlet passage means is located in the vicinity of the greatest width of the mixing tool.
 10. A device for mixing wood shavings, fibers and similar mixtures of wood and waste begasse, especially cellulose containing materials and for simultaneously adding glue thereto, which includes: a hollow rotatable shaft, feeding conduit means arranged within said rotatable shaft in radially spaced relationship thereto so as to define with said rotatable shaft an annular chamber, said feeding conduit means being adapted to be connected to a supply of liquid glue and being provided with passage means therethrough for conveying liquid glue from said feeding conduit means into said annular chamber, and a longitudinal mixing tool connected to and extending outwardly of said rotatable shaft for rotation in a mixing chamber, said mixing tool having an outer free end and being provided with a longitudinal passage communicating with said annular chamber and with outlet passage means including an outer mouth communicating with said longitudinal passage substantially transverse thereto and leading to the outside of said mixing tool, the longitudinal passage in said mixing tool extending through the entire length thereof, and a closure member arranged in the outer free end of said mixing tool and thereby sealing said longitudinal passage at the outer free end of said mixing tool.
 11. A device according to claim 10, in which said closure member is detachably connected to said mixing tool.
 12. A device according to claim 10, in which said mixing tool is detachably connected to said hollow rotatable shaft. 